fix(examples): do not use shadow DOM

This is in preparation for implementing the Testability API and Protractor
end-to-end tests since chromedriver can't handle shadowDom references.

Author: chirayuk

example/web/animation/repeat_demo.dart

@@ -2,6 +2,7 @@ part of animation;
 
 @Component(
     selector: 'repeat-demo',
+    useShadowDom: false,
     template: '''
       <div class="repeat-demo">
       <button ng-click="ctrl.addItem()">Add Thing</button>

example/web/animation/visibility_demo.dart

@@ -17,7 +17,7 @@ part of animation;
       </div>
     ''',
     publishAs: 'ctrl',
-    applyAuthorStyles: true)
+    useShadowDom: false)
 class VisibilityDemo {
   bool visible = false;
 }